Blending of two or more thermoplastic resins is a widely used technique for improving properties of the resin blend, such as heat resistance, impact resistance, toughness, surface hardness, and hygroscopicity. However, as described in, for example, Patent Document 1, when two or more resins are blended, phase separation may occur in the resultant blend.
As described in Patent Document 2, when phase separation occurs in a resin composition produced through blending of resins, in most cases, the resin composition becomes opaque. In general, in order to produce a transparent resin composition exhibiting a phase separation state, resins having similar refractive indices must be blended.
Production of a transparent resin composition through blending of resins and adjustment of the refractive index of the resin composition are carried out through, for example, a method described in Patent Document 3, in which the composition of a grafted resin is adjusted, or a method described in Patent Document 4, in which refractive index is adjusted by incorporation of an additive.
However, such a conventional method encounters difficulty in producing a highly transparent resin composition whose refractive index is readily adjusted.